The basic objective is to define the physiological role of collagenase in the mechanism of bone resorption. Research plans include purification and characterization of the bone collagenase and bone collagenase inhibitor. A radioimmunoassay for collagenase and extracts of various tissues will be devised, studies of inhibition of bone resorption of tissue culture by anticollagenase and collagenase inhibitors will be explored and the relationship between collagen synthesis and collagenase synthesis in cells and culture will be developed.